Missing closing brace/bracket causes segfault

[forivall]

Describe the bug
Most expressions that miss the closing brace (}) or bracket (]) will cause a segfault. Some expressions that miss the closing parenthesis ()) evaluate successfully (although jq errors on these expressions), but specially crafted expressions are able to hit the same segfault.

Version of yq: 4.12.1
Operating system: mac
Installed via: binary homebrew

Command
The command you ran:

yq e --null-input '({"foo": ["bar"}'
yq e --null-input '{"foo": "bar"'
yq e --null-input '[(.bar |= "baz")'
yq e --null-input '({"foo": ("bar"}'

Actual behavior

(some values vary from expression to expression, but are consistent; i'm guessing those are offsets or something in the input. However, the stack is the same for all of the commands)

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x125f3e6]

goroutine 1 [running]:
github.com/mikefarah/yq/v4/pkg/yqlib.(*Operation).toString(0x0, 0xc000230930, 0x1)
	github.com/mikefarah/yq/v4/pkg/yqlib/lib.go:152 +0x26
github.com/mikefarah/yq/v4/pkg/yqlib.(*expressionParserImpl).createExpressionTree(0xc000266820, 0xc00025f840, 0x6, 0x8, 0xc00025f840, 0x6, 0x8)
	github.com/mikefarah/yq/v4/pkg/yqlib/expression_parser.go:49 +0xe5
github.com/mikefarah/yq/v4/pkg/yqlib.(*expressionParserImpl).ParseExpression(0xc000266820, 0x7ffeefbff3ca, 0x10, 0xc000273af8, 0x100f518, 0x20)
	github.com/mikefarah/yq/v4/pkg/yqlib/expression_parser.go:37 +0xf4
github.com/mikefarah/yq/v4/pkg/yqlib.(*streamEvaluator).EvaluateNew(0xc000273d50, 0x7ffeefbff3ca, 0x10, 0x13f3d50, 0xc0000b5d50, 0x0, 0x0, 0x78, 0x132a620)
	github.com/mikefarah/yq/v4/pkg/yqlib/stream_evaluator.go:31 +0x63
github.com/mikefarah/yq/v4/cmd.evaluateSequence(0xc0000b9180, 0xc00007e420, 0x1, 0x2, 0x0, 0x0)
	github.com/mikefarah/yq/v4/cmd/evalute_sequence_command.go:143 +0x816
github.com/spf13/cobra.(*Command).execute(0xc0000b9180, 0xc00007e400, 0x2, 0x2, 0xc0000b9180, 0xc00007e400)
	github.com/spf13/cobra@v1.1.3/command.go:852 +0x472
github.com/spf13/cobra.(*Command).ExecuteC(0xc0000b8f00, 0x0, 0xffffffff, 0xc0000220b8)
	github.com/spf13/cobra@v1.1.3/command.go:960 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
	github.com/spf13/cobra@v1.1.3/command.go:897
main.main()
	github.com/mikefarah/yq/v4/yq.go:11 +0x2a

Expected behavior

Error: Bad path expression, expected close collect brackets at end of expression

Additional context

$ yq e --null-input '({"foo": ["bar"]}'
foo:
  - bar

$ yq e --null-input '({"foo": "bar"}'
foo: bar

evaluates successfully.

jq equivalents

``` $ jq --null-input '([{"foo": ["bar"]]}' jq: error: syntax error, unexpected INVALID_CHARACTER, expecting '}' (Unix shell quoting issues?) at , line 1: ([{"foo": ["bar"]]}

$ jq --null-input '({"foo": ["bar"}'
jq: error: syntax error, unexpected INVALID_CHARACTER (Unix shell quoting issues?) at , line 1:
({"foo": ["bar"}
jq: 1 compile error

$ jq --null-input '{"foo": "bar"'
jq: error: syntax error, unexpected $end, expecting '}' (Unix shell quoting issues?) at , line 1:
{"foo": "bar"
jq: 1 compile error

$ jq --null-input '[(.bar |= "baz")'
jq: error: syntax error, unexpected $end (Unix shell quoting issues?) at , line 1:
[(.bar |= "baz")
jq: 1 compile error

$ jq --null-input '({"foo": ("bar"}'
jq: error: syntax error, unexpected INVALID_CHARACTER (Unix shell quoting issues?) at , line 1:
({"foo": ("bar"}
jq: 1 compile error

</details>

[mikefarah]

Fixed in 4.13.0